Methodology — Face Rater

Face Rater's free analysis is a deterministic geometry calculation, not an AI opinion. The same photo always produces the same numbers. This page documents exactly what is measured, how scores are derived, and where the method's limits are.

The pipeline

1. Detection. Your photo is analyzed locally in your browser by MediaPipe Face Landmarker, which returns 478 facial landmarks as normalized coordinates. The original photo never leaves your device in the free tier.
2. Quality gates. We refuse to score a photo when no face is found, when more than one face is found, when the head is turned too far from the camera (estimated from left/right cheek and eye-region width asymmetry), or when the image is too blurry. No face, no forced score.
3. Preprocessing. Head roll (tilt) is estimated from the line between the outer eye corners and corrected before scoring. Normalized coordinates are converted to a consistent pixel scale — raw normalized x/y values are never compared directly, because x scales with image width and y with image height.
4. Scoring. Three sub-scores are computed and combined into a 0–100 reference score.

What we measure

Symmetry (40% of the score)

• Mid axis: estimated from a combination of the midpoint between the eye centers, the nose bridge, and the philtrum — never from the nose-tip x-coordinate alone, which is easily skewed by pose.
• Compared pairs (at minimum): outer eye corners, inner eye corners, cheeks, brows, and mouth corners. Each pair's deviation from a perfect mirror across the mid axis is measured as a percentage of visible face width.
• Example output: "Your left eye sits about 1.2% higher than your right (relative to face width); overall symmetry is within the reference band."

Visible face proportions (35% of the score)

• Width-to-height: visible face width ÷ visible face height, where height runs from the top-of-face landmark (MediaPipe point 10) to the chin (point 152). Point 10 is not the hairline — we do not claim to measure classical "three-section" facial thirds, only the face visible in the photo.
• Segment ratios: brow-to-nose-base and nose-base-to-chin distances relative to the middle segment, using available landmarks.

Eye-area harmony (25% of the score)

• Inner-canthal distance ÷ visible face width — how far apart the inner eye corners sit, relative to the face.
• Eye-width symmetry — the percentage difference between left and right eye widths.

From measurements to the score

Each sub-score maps the measurement's distance from a reference band onto 0–100: inside the band scores high, and the further outside, the lower. The overall score is a weighted sum — 40% symmetry, 35% proportions, 25% eye-area harmony — mapped to 0–100, then assigned a tier:

• 85–100 Harmonious
• 70–84 Balanced
• 55–69 Developing
• below 55 Starting Point

These tiers describe photo geometry bands, not people. "Developing" and "Starting Point" describe how far the photo's measurements sit from our reference bands — often a lighting or angle artifact — and are not judgments of anyone's face.

Reference ranges: initial values, pending calibration

The reference bands are initial, deliberately wide values. They have not yet been calibrated against a licensed, diverse sample set, and they are not scientific facts or population norms. Until calibration is complete, every score display carries this caveat. If calibration shifts the bands, we will update this page and say so.

Stability rule

A scoring method that jumps between tiers when the same photo is slightly resized or tilted is not measuring anything real. Our acceptance rule: if a sub-score cannot stay stable under minor scaling and rotation correction, that sub-score is downgraded to "not scored" and reported without a number. We would rather show two stable measurements than three noisy ones.

Known limits

• One front-facing photo. Profile features (nasal projection, chin projection, forehead slope) are invisible from the front and are reported as "not scored — needs a side photo," never guessed.
• Photo conditions move the numbers. Lighting direction, head pose, lens focal length, camera distance, and device all shift measurements by a few points. Arm's-length selfies distort proportions most.
• 2D projection of a 3D face. A photograph flattens structure; geometry on a photo is not geometry on a face.
• Not medical. Nothing here is medical, dermatological, or cosmetic-surgery advice.
• No trait inference. We never infer intelligence, trustworthiness, competence, personality, age, or health from a photo.